1. Field of the Invention
The present invention relates generally to the field of anesthetizing a patient and more particularly to a method of anesthetizing a patient with the use of a gas delivery device which was previously only known to be used in oxygenating a patient's blood intravenously. The device can be positioned within a patient's body (e.g. in the inferior vena cava, superior vena cava, the right atrium of the heart, or any combination thereof) and then utilized to administer an anesthetic gas directly into the blood stream.
2. Description of the Prior Art
Various methods have been used for many years in anesthetizing a patient so that surgical procedures can be performed without considerable discomfort to the patient. Ether or other gases have been delivered orally to patients, and, in more recent years, anesthetic drugs have been delivered by needles directly into a patient's blood vessel. While these systems have been satisfactory for the purposes intended, there are instances wherein they may add an added level of complexity and possibly discomfort to a patient.
More particularly, in recent years and particularly during open heart surgery or the like wherein it has been necessary to bypass the heart and lungs in order to perform various surgical procedures, the blood has been oxygenated by exposing the blood to various types of oxygenators. One type of oxygenator is commonly referred to as a membrane oxygenator and utilizes a plurality of small fibrous membranes which are gas permeable and positioned in a stream of blood so that oxygen delivered to the interior of the membranes can diffuse through the walls of the membranes into the blood while CO.sub.2 from the blood cross diffuses into the interior of the membranes for removal from the device. More recently, membrane oxygenators have been designed for intravenous placement in the interior vena cava of a patient so that the blood can be oxygenated without having to remove it from the body. This latter type of membrane oxygenator is referred to as an intravenous membrane oxygenator and examples of such are disclosed in U.S. Pat. No. 4,911,698 for a PERCUTANEOUS OXYGENATOR invented by Brack G. Hattler; U.S. Pat. No. 4,986,809 for an IMPROVED PERCUTANEOUS OXYGENATOR invented by Hattler, et al.; co-pending application Ser. No. 676,262, filed Mar. 27, 1991 for an INFLATABLE PERCUTANEOUS OXYGENATOR invented by Brack G. Hattler; U.S. Pat. No. 4,583,969 of Mortensen; U.S. Pat. No. 4,850,958 of Berry, et al.; and U.S. Pat. No. 4,631,053 of Taheri. lntravenous membrane oxygenators have been developed exclusively for oxygenating blood intravenously and alternative uses to applicant's knowledge have never been contemplated.